This research will test the hypothesis that interpersonal stressors affect the course of rheumatoid arthritis (RA) among women (age 55-75) through activation of the endocrine and immune systems. RA is a progressive systemic disease involving disturbance in the regulation of the neuroendocrine and auto-immune systems. In our prior research, we found strong evidence that a key factor in RA disease progression may be the patient's reactivity to life circumstances: Stressful events appear to have a greater impact on the physiological responses and mental health of RA patients as compared to OA patients. This study is designed to examine this hypothesis by following RA patients over time with repeated measures to assess their psychological and physiological reactions to naturally occurring interpersonal stressor events. Their reactions will be compared to the reactions of OA patients and healthy controls, matched in age and marital status. 80 female rheumatoid arthritis (RA) patients, 80 female osteoarthritis (OA) patients, and 80 healthy controls will be interviewed weekly by telephone to assess interpersonal stress levels and monitor disease state, after an initial baseline assessment. Coincident with a baseline interview, during a period of increased interpersonal stress and a period of disease flare among the patient groups, clinical assessments of disease state will be made and blood samples drawn. The blood samples will be analyzed to detect changes in levels of stress hormones, and immune parameters between baseline and a time of stress, and between baseline and a time of flare, for each group.